Security operations centre
Also known as SOC
The team and tooling responsible for monitoring, investigating, and responding to security events.
A SOC is people first. Continuous coverage needs enough analysts to staff every hour including holidays, plus the tiering to escalate something genuinely serious, which is why building one in-house is out of reach for most businesses below enterprise scale.
What matters operationally is not whether the letters appear in a proposal but whether someone with authority is watching at 2am on a Sunday and can act without waiting for you to answer the phone.
Where this comes up
Security operations centre sits inside our cybersecurity and threats work. If you are trying to work out what this means for your own environment rather than in the abstract, that is the page worth reading next, and a short call will get you a straight answer faster than either.